Electric heater



Dec. 12, 1933. l. LUBBOCK ETAL 1,939,125

ELECTRIC HEATER Filed NOV. 16, 1931 Patented Dec. 1.2, 1933 ELECTRIC HEATER f Isaac Lubbock and John Ruskin Joyce, London, England, assignors to The Asiatic Petroleum Company Limited, London, England Application November- 16, 1931, serial No.

575,414, and in Great Britain December 16,

4 claims.' (cl. 21e-,38)

Our invention relates to improvements in electric heaters, and more particularly to heaters of the immersion type.

Heaters at present commercially employed for 5,- heating oils are usually sheathed in an insulating jacket as in the case of water heaters with the result that, the heating being indirect, the resistance wire forming the heating element has to be raised to high temperatures and caking of oil -;l occurs on the surface of the sheath. Moreover in such heaters only one face of the wire is actively employed in the process of heat transference.

According to the present invention, the insulating sheath is dispensed with and a strip of is resistance wire is wound in one direction around a skeleton former with the turns in spaced relai tionship so that substantially the whole surface of the wire (exceptwhere it contacts with the skeleton former) is available for directly heating -20- the oil.

` The invention is illustrated in the accompanying drawing in which Figure 1 is a sideelevation partly in section, Figure 2 a section on the line II-II Figure 1, Figure 3 a section on the line -2Q- IlI-III Figure 1, and Figure 4 a local section on the line IV-IV Figure 2.

The skeleton former comprises four horizontal circular rods 1, 2, 3, 4 of the substance known "under the registered trade mark Bakelite, fibre i340 or other insulating material which extend from a headpiece 5 in spaced relation corresponding to I the four corners of a rectangle, the ends of the rods being reduced in diameter at 6 to enter corresponding apertures formed in the head 5. The yagi outer ends of the rods are tapped to receive screws 7 for securing an end plate 8 to the rods to unite them at their outer ends. The rods are formed along their length with spaced grooves 9 for the reception of the resistance wire indicated at 10. :140 Terminal posts are fitted into the head in such a manner that they are insulated electrically from the head 5 and yet afford a perfect seal against egressrto the liquid being heated in the vessel to which the heater is fitted.y A45 In the arrangement illustratedvthe head 5 is drilled to receive the terminal posts which are formed in two portions 11, 12, each of which is provided with a flange 13, one portion being tapped to receive a screw-thread on the other por- ;59 tion to enable the portions to be clamped togetheragainst the head. Washers 14 of fibre or other insulating material are interposed between the flanges and the head, and insulating sleeves 15 are interposed between the posts and the head.

One end of the resistance wire 10 is secured to one of the terminal posts and is wound round one pairof upper and lower posts and then roundthe other pair of upper and lower posts, the wire'being laid in the grooves and forming two flattened helical coils, the turns of which are spaced by the Y grooves., The free end of the wire is then secured to the other terminal post.

Preferably the inner side of the head is grooved to accommodate a fibre shield 16, which separates one terminal post from the other.

Preferably also each pair of upper and lower rods 1, 2 and 3, 4 is inter-connected by a pair of struts 17, 18 to increase the rigidity of the skeleton former.

The head piece 5 may, as shown, be'screwthreaded to be screwed into the wall of the container in which the oil to be heated is contained, or may be otherwise adapted for attachment to the container as for example by means of va flange connection.

In a modification the rods are moulded to form a one piece skeleton former and if desired in one piece with the end pieceand the struts.

In place of remploying two flattened helical coils we may employ any desired number which 8,0 may be connected in series or in parallel or some in series and some in parallel.

It will be seen that with the construction according to our invention direct heating is `obtained and that by virtue of the spacing of the turns of the resistance wire, the liquid is a1- lowed to come into contact with the wire throughout substantially the whole of its extent.

We have found that with a heater constructed according to the invention there is no carbonizingof the resistance wire, that cheaper resistance metal can, if desired, be employed, and that higher ratings are possible in a given size of heater.

Obviously the invention can be employed for heating liquids of a non-conducting nature other than oils.

What we claim is:-

1. An electric immersion heater comprising a head portion adapted for liquid-tight connection v with a receptacle for liquid to be heated, terminals extending through said head part and electrica'lly insulated therefrom, the said terminals being. disposed liquid-tight in said head part,

Aa former part of skeleton form attached to said head part, and resistance wire wound about said former part with its turns in spaced relation, firstly in a direction away from the head part towards the end of the former part and then back from this endk to the head part, Vthe ends of thev 10 said resistance wire being in electrical connection with the terminals extending through the l3. A heater as claimed in claim 1 in which Y t t the skeleton former part comprises four posts located symmetrically in spaced relationship and in which the resistance` wire is wound rstly around one pair of posts in a direction away from .the headrpart and then around the other pair in a `direction towards the head part.

4. jA heater as claimed in vclaim 1, inv which the y terminals are separated by a shield.

" ISAAC LUBBOCK.

vJOI-IN RUSKIN JOYCE.

Yies 

